The Complete Fox DHX 3/4/5 Service Thread

Hi all

Here is the 4th Version of my Fox DHX 3/4/5 Service Guide

It shows you how to completely service (about 98%) your DHX, including the rebound and propedal assemblies. Servicing the rebound assembly will require careful use of a propane torch, so before commencing work on your shock, be sure you uderstand what you are doing by first reading the method in which to use the propane torch.

Make sure you download and read through the tutorial carefully before commencing work on your shock

For start I would like to thank you for the guide NICK...I`ve got a problem with my shock FOX DHX 5.0 2008 and i can`t figure out what`s wrong..I hear a sound like a knock inside the shock ....I always ride with 125 psi in the air chamber so the air its not the problem .. For example my shock become very strong at compression when i rotate the rebound knob clockwise (10-15 click) and the sound is very strong and afect the performance of the shock ....The same thing happen when i am activating the propedal , but the sound seems to double (2 knocks at one time )....I am waitng an answer from you NICK ....THX ..great job

No way to actually get the o-ring sizes from you, is there? Would be great to be able to order them and have them on hand at the start. Don't know of any place I could go to get them sized exactly either. Anyone have a good spot in the San Francisco area? Peninsula preferably...

Hey Nick, Thanks for all the research and development on this very comprehensive guide!

I ran into a bit of a snag with my rebuild,

When I go to take the lockring off of the piston assembly the entire cylinder starts to loosen from the black carriage instead of the lockring itself. I've tried putting it very tightly in a vice among other more barbaric things and was wondering if you had any advice for this scenario.

its not the piston bolt i am very sad ..dont know what to do ....help me guys with some ideas

Ok sorry guys for leaving this thread dead for awhile, have been mega busy starting my new life at college and Uni

EDIT: ok just checked and read that you dont got a 05 model DHX
Ill be honest, im quite stumped at what could be causing this

Hmm...

Well make sure you double check that you havent overtightened the piston bolt, as this is the cause of the problem 85% of the time. Failing that, did you remove the PP assembly? If you did are you sure that you put all the springs and such back together properly?, and also check to make sure the snap ring is resting in its groove properly

Hey Nick, Thanks for all the research and development on this very comprehensive guide!

I ran into a bit of a snag with my rebuild,

When I go to take the lockring off of the piston assembly the entire cylinder starts to loosen from the black carriage instead of the lockring itself. I've tried putting it very tightly in a vice among other more barbaric things and was wondering if you had any advice for this scenario.

Thanks,

Dave

Hi Dave

Now when you say lockring, do you mean the snap ring inside the Resi that holds the PP assembly in, or are we talking about the piston bolt? the thing that holds the piston and shims on?

If its the piston bolt thats stuck and causing the shaft to unthread from the rebound housing eyelet (the black thing at the bottom of the shaft in which the red rebound adjust resides) then to get in undone, first clamp the shaft as tight (being careful not to damage the shaft finish) as you can into wooden clamps as is shown in my guide, then use a propane torch to GENTLY heat the top of the shaft underneath the piston (where the tiny hole is) make sure you heat it evenly, and only until its hot to touch. Now the bolt should come of much easier now, if not, make sure its firmly clamped and give it a tiny bit more heat.

to clarify i'm talking about step 4. in the guide. the entire cylinder is coming unthreaded from the black turn around instead of just the piston cap. so in short i can't get the piston out the cylinder. hopefully you know a trick for me!

Well in that case, my fix would be the same as what i said above.
Make some shaft clamps outta some hardwood off cuts and clamp the entire cylinder firmly into the vice (with the clamps of course). Just be careful not to crush it.

Then again, using a propane torch, heat up the cylinder where the shaft housing (the black thing in which the shaft goes into) screws into it, heat around that area evenly until it is hot to touch, then making sure the cylinder is firmly clamped, undo the shaft housing. This should get it undone, Fox dont loctite it, but it gets torqued fairly high, mine was tight to undo the first time as well, but the propane torch fixed that.

One more thing, seeing as you said that the cylinder was unscrewing from the main body, make sure that when you have removed the piston and the shaft that you flip the thing around, again clamp it, and tighten the main housing (the black bridge that connects the main cylinder to the resi. You will have to use a breaker bar and insert it through the mount hardware to get enough leverage to tighten it , as hand tight wont be enough.

Hope this helps, let us know how it goes and if you got anymore questions, dont hesitate to ask!

A little update guys, have been poking round through the files of the fox service site that used to be uploaded here, and have stumbled across this IFP Depth chart

As you can see, the depths differ for the DHX 3/4 compared to the 5, which makes sense because the increased IFP depth figures for the 5 are compensating for the bottom out adjuster (which is simply a screwable plug that increases or decrease the volume of the boost valve chamber.)

Here it is, will update the one in the guide soon....
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DHX 5.0 Coil IFP Depth:
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It is a great guide, though I have a completely newbie, mechanical retarded ingenieur, a term glosary could be great , even a graphic glossary of all the parts, so we all know (those who we have no idea) understand also completely. =)

A list of the small parts could be useful, especially if they could be cross referenced with Fox part numbers to make replacing things easier. If anything, a list of the o-ring sizes would be great to have in the guide to avoid having to run to the hardware store midway through the job.

In terms of the major components, I thought the photos did a good job showing what was what. It might be interesting to know what is interchangeable between different shock models and sizes, but that's more of a personal curiosity.

maybe guides for complete dummys who have absolutely no idea.. would actually be great, lets say, in the engineering world, most of the procurement specifications are done in a way a kid could understand them. At least thats they it should be to avoid daylong meetings with a bunch of engineers who cannot read engineering specifications :P

I was trying to set my Fox DHX 4.0 on my 2008 Reign 0, Fox manulas were brief, confusing and useless...

Stock shim stack differs from year to year, i only know the stock shim stack for a 09 DHX 5

With the o-rings, its best to take the old ones to a supply store and have them sized for new ones, ensures you get the correct size ones

Main reason i dont bother with measuring and posting the sizes is because i dont got a good set calipers, and the conversion between metric and imperial is annoying (when are you americans gonna see the light and swap to metric!!!!)